A lever hoist failed causing a load to descend to deck in an uncontrolled manner. The near miss incident occurred when a set of 1m trenching swords were being lowered to deck. The lever hoist being used was rated to 1.6Te, more than capable of lifting the load which was approximately 200kg in weight.
The rigging arrangement used was correct and all items of rigging had been recertified by a competent authority in recent months, including a limited load test.
What were the causes? What went wrong?
- On investigation and inspection, worn cog teeth were found. A toothed part of the gear assembly (see figure 1) was found to have excessive wear;
- This gear assembly was not visible without stripping the unit, so wear would not have been evident during pre-use checks. Strip down of a working unit would invalidate the manufacturer’s warranty and certification;
- Our member noted that a thorough examination cannot be conducted in situ and units must be taken to a workshop for full examination.
Our member took the following actions:
- Review and amend the process for recertification of rigging with moving / wearing parts;
- Arrange for supply of newly certified rigging lofts on a 6-monthly basis;
Revised internal documentation on lifting operations appropriately.